bug symfony#13527 [Validator] drop grapheme_strlen in LengthValidator (nicolas-grekas)

This PR was merged into the 2.3 branch.

Discussion
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[Validator] drop grapheme_strlen in LengthValidator

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#13491
| License       | MIT
| Doc PR        | -

As stated in symfony#13491, validating the length of a string with grapheme_strlen is not suited to validating input because a very long string can in fact have a length of 1 when counted with grapheme_strlen.
Counting UTF-8 characters (not clusters) is not subject to this problem.
The attached patch removes using grapheme_strlen but also adds more fallback when couting the length of strings, using iconv (which is more broadly avail. than mbstring) or PCRE for UTF-8 strings.

Commits
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915fcd8 [Validator] drop grapheme_strlen in LengthValidator

Author: fabpot

src/Symfony/Component/Validator/Constraints/LengthValidator.php

@@ -35,12 +35,20 @@ public function validate($value, Constraint $constraint)
 
         $stringValue = (string) $value;
 
-        if (function_exists('grapheme_strlen') && 'UTF-8' === $constraint->charset) {
-            $length = grapheme_strlen($stringValue);
+        if ('UTF8' === $charset = strtoupper($constraint->charset)) {
+            $charset = 'UTF-8';
+        }
+
+        if (function_exists('iconv_strlen')) {
+            $length = iconv_strlen($stringValue, $constraint->charset);
         } elseif (function_exists('mb_strlen')) {
             $length = mb_strlen($stringValue, $constraint->charset);
-        } else {
+        } elseif ('UTF-8' !== $charset) {
             $length = strlen($stringValue);
+        } elseif (function_exists('utf8_decode')) {
+            $length = strlen(utf8_decode($stringValue));
+        } else {
+            preg_replace('/./u', '', $stringValue, -1, $length);
         }
 
         if ($constraint->min == $constraint->max && $length != $constraint->min) {